Abstract A refractive sensing unit is provided for use with manometer gages, or the like, and which may be set to monitor the liquid in the manometer at any particular level. The unit responds to the refraction of light passing through the liquid, so as to exhibit high immunity to interference from ambient light, and to be capable of performing its function in conjunction with translucent manometer liquids. The sensing unit is attached to the manometer tube by means of a clip which enables the unit to be moved up and down the tube to any desired detecting level, and it does not interfere with the conventional visual readings of the usual graduated scale strip mounted adjacent the tube. A light source is mounted in the sensor unit, together with a photoelectric transducer, and these elements are fixed at an angle to one another so that light reaches the transducer from the light source only when the effective refractance of the manometer tube produces the correct deflection of the light from the source to be directed to the transducer. A sensitive electronic detector circuit is provided which operates in conjunction with the sensing head to activate an alarm, or other appropriate visual or aural indicator, when the manometer liquid falls below or rises above the monitored level.
An optical sensor for detecting when a liquid in a transparent tube drops below a particular level, said sensor comprising: a head to be mounted on said tube at the particular level; a light source mounted on said head in position to direct a beam of light through the tube when the head is mounted on the tube; an electronic circuit connected to said light source to introduce an oscillatory electric signal to said light source to cause said light source to emit a pulsating light beam; a light sensitive detector mounted on said head at a predetermined angle with respect to said light source in position to receive the pulsating light beam from said light source as refracted by the wall of the tube when the liquid in the tube drops below the predetermined level, said light sensitive detector responding to the pulsating light beam to generate a corresponding oscillatory electric signal and to introduce said last-named signal to said electronic circuit to establish a locked condition in said electronic circuit as long as the intensity of the pulsating light beam received by said light sensitive detector exceeds a predetermined threshold; and electrically energized means connected to said electronic circuit to be activated only when the aforesaid locked condition in said circuit is established.
Claim 2
Dependent Claim
215 words
An optical sensor for detecting when a liquid in a transparent tube drops below a particular level, said sensor comprising: a head to be mounted on said tube at the particular level; a light source mounted on said head in position to direct a beam of light through the tube when the head is mounted on the tube; an electronic circuit connected to said light source to introduce an oscillatory electric signal to said light source to cause said light source to emit a pulsating light beam; a light sensitive detector mounted on said head at a predetermined angle with respect to said light source in position to receive the pulsating light beam from said light source as refracted by the wall of the tube when the liquid in the tube drops below the predetermined level, said light sensitive detector responding to the pulsating light beam to generate a corresponding oscillatory electric signal and to introduce said last-named signal to said electronic circuit to establish a locked condition in said electronic circuit as long as the intensity of the pulsating light beam received by said light sensitive detector exceeds a predetermined threshold; and electrically energized means connected to said electronic circuit to be activated only when the aforesaid locked condition in said circuit is established.
Claim 3
Dependent Claim
32 words
The optical sensor defined in claim 1, in which said light source comprises a light emitting diode, and a lens mounted on said diode for forming a light therefrom into a beam.
Claim 4
Dependent Claim
46 words
The optical sensor defined in claim 2, in which said light emitting diode emits light in the red-infra-red region of the radiation spectrum, and in which said light sensitive detector comprises a phototransistor with a spectral sensitivity centered in the red-infra-red region of the radiation spectrum.
Claim 5
Dependent Claim
34 words
The optical sensor defined in claim 1, and which includes clip means attached to said head for mounting said head on the tube so as to permit movement of the head along the tube.